Altered patterns of protein glycosylation and increased levels of serum proteins are often hallmarks of human diseases. Elevated serum levels of the glycoprotein gamma-glutamyl transpeptidase (GGT) are commonly seen in patients with tumors of the liver and pancreas and in patients with non malignant forms of liver and pancreatic diseases. An accumulating body of data indicates that GGT possesses tissue-specific and tumor-specific glycoforms that could be used to distinguish patients with cancer from those with other pathologies. My study will focus on the identification and characterization of tissue- and tumor-specific glycans on GGT. This study has three specific aims, which incorporate the use of state-of-the-art fluorescent HPLC and mass spectrometric techniques for glycoanalyses. The first specific aim is to identify tissue-specific glycoforms on GGT isolated from normal pancreas and liver tissue. The second specific aim is to identify tumor-specific glycan species on GGT isolated from tumors of the pancreas and liver and on GGT shed into the serum of patients with these malignancies. The third specific aim of this proposal is to develop antibodies against tissue- and tumor-specific glycoepitopes on GGT and to evaluate the sensitivity and specificity of these antibodies for detecting tissue- and tumor-specific GGT species in sera derived from non-diseased individuals and patients diagnosed with pancreatic adenocarcinoma, hepatocellular carcinoma, and non-malignant diseases of the pancreas and liver. These studies will also provide insight into the mechanism by which GGT is released from cellular membranes into serum during tumorigenesis. The timely and accurate diagnosis of pancreatic or liver cancer is critical for maximizing the efficacy of therapeutic treatments. This work will establish a foundation for the development of a serum-based immunoassay for the early detection of these malignancies using glycoepitopes on GGT shed into the serum. Lay summary: Survival rates for patients diagnosed with either pancreatic or liver cancer are very low. This is largely due to the fact that these two forms of cancer typically go undetected until patients begin showing disease symptoms, which are most often associated with advanced stages of the disease. I propose to identify and characterize novel blood markers that can be used to develop screening tests for the early detection of pancreatic and liver cancer at a stage when the cancerous tissues are the most responsive to therapeutic treatments. Page 2 Number pages consecutively at the bottom throughout Form Page 2